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Luigi Auriemma
Application: Trend Micro OfficeScan Corporate Edition
http://us.trendmicro.com/us/products/enterprise/officescan-client-server-edition/
other Trend Micro products could be affected by this
vulnerability since it's located in a function used to
decrypt a specific type of passwords used by this vendor
Versions: <= v8.0 Patch 2 - build 1189
<= v7.3 Patch 3 - build 1314
Platforms: Windows
Bugs: A] buffer-overflow in the decryption function of the
passwords
B] endless dead processes
Exploitation: remote
(no tests have been performed to check for a possible
local exploiting of the vulnerability on the clients
machines for killing the antivirus or the monitor
processes or escalating privileges)
Date: 27 Feb 2008
Author: Luigi Auriemma
e-mail: aluigi@autistici.org
web: aluigi.org
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1) Introduction
2) Bugs
3) The Code
4) Fix
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1) Introduction
===============
OfficeScan is an anti-virus client and server developed by Trend Micro.
The server is mainly a set of CGIs, ActiveX and web pages which run on
a pre-existent web server or on the included Apache installation.
As already written in the header of this advisory the vulnerability
could affect other products too.
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2) Bugs
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A] buffer-overflow in the decryption function of the passwords
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The first time I saw the so called OfficeScan's passwords was almost
two years ago and in short they are just MD5 hashes of the original
password plus an additional encryption, but I was never interested to
go deeper in the matter and I don't know if something has been changed
from that time.
I wrote something incomplete about them a lot of time ago in case
someone is curious or want to add something:
http://aluigi.org/pwdrec/officescan_pwdmd5.txt
The function for decrypting these data is ever the same one used in
"any" program that needs to handle this type of passwords, so the CGIs
which read the password of the admin/user who wants to log in the web
management (for example cgiChkMasterPwd.exe), the PolicyServer
(policyserver.exe which receives the client's password from the
cgiABLogon.exe CGI) and naturally the same server and all the clients.
In short the function verifies that the input password starts with the
!CRYPT! string and then copies the subsequent data in a stack buffer of
512 bytes without verifying its correct length with the obvious result
of a buffer-overflow.
Not all the versions of OfficeScan can be exploited for executing
malicious code (7.3 is fully exploitable) because on some of them (like
the latest 8.0) the exception handler terminates the process if notices
a stack corruption and so in these cases the only effect can be a
Denial of Service (like what happens with the PolicyServer where current
and new users can no longer use the service, in fact although exists the
auto-restarting function it will not work until the dead process is not
killed or the error message acknowledged) or just a dead process which
will not affect the correct usage of the services.
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B] endless dead processes
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The following vulnerability is reported here only for thoroughness and
is very simple: a couple of NULL pointer vulnerabilities in the CGI
executables used by the server can be exploited to create endless dead
processes on the server causing a possible Denial of Service after many
of them.
These NULL pointers are caused by two factors: the lack of the
Content-Length field in the HTTP request and the usage of invalid
sequences of chars in the CGIs parameters (both of them have been
tested on the included Apache server).
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3) The Code
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http://aluigi.org/poc/officescaz.zip
nc SERVER 8080 -v -v < officescaz1.txt
nc SERVER 8080 -v -v < officescaz2.txt
nc SERVER 8080 -v -v < officescaz3.txt
nc SERVER 8080 -v -v < officescaz4.txt
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4) Fix
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No fix
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